RAID 0 reconstruct from disk images

Daenris

This is Linux (Ubuntu Gutsy) but can be done on Windows if anyone knows of software that would help.

I had 2 1.5 external enclosures (Fantom) that have recently failed. They were made up of 2 750GB drives in a RAID 0 configuration (handled by the enclosure controller, not set up by me). As far as I can tell the failure is enclosures only -- the drives themselves appear fine. I placed each drive in a different single drive enclosure and was able to copy off the entire drive with dd (actually ddrescue) with no errors, so I now have images of the drives stored here.

I can recover the data from onsite tape backups if necessary, but have been told by the people that handle the backup system that it's a long and painful process. I'd like to skip that, if possible, by reconstructing the image files I have back into a RAID 0 array to copy the data off.

So far, I've tried attaching the image files to loop devices (losetup), then constructing those into a RAID 0 with mdadm with a few different stripe sizes (64/128) with no success yet. I'm obviously going to continue going at it, but I wondered if anyone here who was Linux knowledgeable had any other ideas about how to reconstruct a RAID 0 from raw disk images.

PirateJon

You know who uses raid 0? People that hate data.

have been told by the people that handle the backup system that it's a long and painful process

Then they have a shitty backup process or are just lazy in addition to hating data. Get them on that shit yesterday.

add- because if your tricks won't work (they wont) then the quicker they get started the quicker it gets done.

FyreWulff

There's an old joke.. RAID 0 stands how how much data you're gonna get back when it fails.

Get them to restore it, because that's the only way you are getting it back.

darkmayo

I think he said the enclosure failed but the drives are ok. He should be able to rebuild the array, but if one of those drives failed then yea he'd be fucked.

EclecticGroove

There can be tons of problems rebuilding an array with different controllers. If he has a non defunct enclosure of the same type around, he should be able to use that to rebuild it.

Baring that, I don't know of any way to set up a virtual raid array with existing disks.

Daenris

Yeah, the drives are all fine -- at least they are accessible via a different enclosure and I'm able to do a raw dump with no errors, so seemingly fine. I don't have another working enclosure of the same, though I'd considered getting one, but the price and time makes it not really worth it. I'm pretty much planning on having to recover from tape -- though we can't start until our new storage comes in -- but figured I'd give it a shot in the meantime.

I was hoping to be able to access the data by rebuilding a RAID 0 array with the copied disk images, but so far have been unsuccessful (and have been able to get almost no data from the company's tech support about the structure of their enclosures' RAID).

PirateJon

The thing with raid 0 is striping and unless you can identically read the stripes in the same manner they were written, the data is gibberish.

Chalkbot

I have successfuly rebuilt RAID 0 arrays and gotten all my data before, but I've also not been able to in seperate circumstances, so it can go either way in my experience.

While I have limited experience with RAID data recovery, I do have a good amount of experience with tape backup systems and I can say that would be way easier. Whoever told you it was going to be a pain either doesn't know what they're doing or would rather not do anything, so is just making excuses. It's literally like 20 minutes of work tops to find the correct tape and set the propper restore operation. Unless you guys have a storage room full of unlabled tapes or something.

Daenris

Chalkbot wrote: »

I have successfuly rebuilt RAID 0 arrays and gotten all my data before, but I've also not been able to in seperate circumstances, so it can go either way in my experience.

While I have limited experience with RAID data recovery, I do have a good amount of experience with tape backup systems and I can say that would be way easier. Whoever told you it was going to be a pain either doesn't know what they're doing or would rather not do anything, so is just making excuses. It's literally like 20 minutes of work tops to find the correct tape and set the propper restore operation. Unless you guys have a storage room full of unlabled tapes or something.

I realize it's not as much of a pain as they're making it out to be as I've worked with tape backups in my previous job, and it's likely what will happen once we get our new storage available to restore to since I haven't had luck yet with the RAID recovery, but it's also certainly not a matter of just finding the 1 tape as it's nearly 3TB of data, and they do have a lot of tapes as they're backing up our data in addition to other groups with equal or larger data storage requirements.

Thanks for the help everyone. I was hoping someone would have a suggestion for some other tricks or methods to try, but it looks like I'll just wait a few days for our storage and do the restore from tape. Thread can be locked.